Fix a regression in the hyperscale creation

bite/telemetry/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 3.1.3 on 2021-03-19 08:08
+# Generated by Django 3.1.7 on 2021-03-25 10:55
 
 import django.core.validators
 from django.db import migrations, models
@@ -18,7 +18,7 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='Telemetry',
             fields=[
-                ('id', models.AutoField(primary_key=True, serialize=False)),
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                 ('time', models.DateTimeField(auto_now_add=True, db_index=True)),
                 ('transport', models.CharField(choices=[('http', 'http'), ('mqtt', 'mqtt')], default='http', max_length=4)),
                 ('clock', models.IntegerField(null=True, validators=[django.core.validators.MinValueValidator(0)])),
@@ -28,6 +28,7 @@ class Migration(migrations.Migration):
             options={
                 'verbose_name_plural': 'Telemetry',
                 'ordering': ['-time', 'device'],
+                'unique_together': {('time', 'device')},
             },
         ),
     ]

bite/telemetry/migrations/0002_timescale.py

@@ -0,0 +1,24 @@
+# Generated by Django 3.1.7 on 2021-03-25 10:55
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('telemetry', '0001_initial'),
+    ]
+
+    # Timescale requires an hyperscale table to have the field used for the
+    # partitioning ('time') to be in the any UNIQUE constraint.
+    # Because of that we have a unique_together on 'time' and 'device_id',
+    # however Django always adds an 'id' as PRIMARY_KEY.
+    # Django's 'id' isn't used as a foreign key, so we are dropping
+    # the contraint and simply adding an index to the 'id' columns.
+    # We can now create the hypertable.
+    operations = [
+        migrations.RunSQL(
+            "ALTER TABLE telemetry_telemetry DROP CONSTRAINT telemetry_telemetry_pkey ;"  # noqa: E501
+            "CREATE INDEX telemetry_telemetry_id_idx ON telemetry_telemetry(id);"  # noqa: E501
+            "SELECT create_hypertable('telemetry_telemetry', 'time');"),
+    ]

bite/telemetry/models.py

@@ -30,7 +30,6 @@ def telemetry_validation(value):
 
 
 class Telemetry(models.Model):
-    id = models.AutoField(primary_key=True)
     device = models.ForeignKey(Device, on_delete=models.CASCADE)
     time = models.DateTimeField(db_index=True, auto_now_add=True)
     transport = models.CharField(max_length=4,
@@ -43,6 +42,7 @@ class Telemetry(models.Model):
 
     class Meta:
         ordering = ['-time', 'device']
+        unique_together = ['time', 'device']
         verbose_name_plural = "Telemetry"
 
     def __str__(self):